Maybe the top-off kit is a BMW thing. Most other brands don't need it. Is there a message from the on-board computer that tells one when to top-off? I think I would also check into a windshield washer top off kit, too. Then there is the transmission and p/s, and don't forget the brake fluid. You could put them with the spare fan belt, fuses and bulbs, right next to the air compressor and the flares, beside the first aid kit, blanket, sand, drinking water, jumper cables, chains and tow strap and 50/50 coolant mix and flashlight.